Air conditioning unit having low fan speed over-ride means



June 26, 1962 L. w. ATCHISON AIR CONDITIONING UNIT HAVING LOW FAN SPEED OVER-RIDE MEANS Filed Dec. 22, 1960 IN V EN TOR.

LEONARD W. ATCHI SON HIS ATTORNEY F'IGJ put of the air conditioner.

atet nice 3,040,543 Patented June 26, 1952 a 3 040 543 AIR coNnmoruNd Urur HAVING Low FAN TSPEED VER-RIDE MEANS Leonard W. Atchison, Louisviile, KyL, assignor to General Electric Company, a corporation of New York Filed Dec.,22, 196i), Ser. No. 77,657 Claims. (Cl. 62-481) The present invention relates to an air conditioning unitand more particularly to an air conditioner having a multi-speed fan arrangement and means for over-riding the low fan speed control whenever the unit is subjected to-overload conditions. I

Air conditioners of the self-contained type normally in-' clude a refrigeration system mounted within a case that is partitioned into compartments exposed to indoor and outdoor air respectively. The refrigeration system includes a heat exchanger mounted 'within each compartment and connected in refrigerant flow relationship with a compressor, also mounted in the unit. A fan in the outer compartment circulates outdoor air over the outer heat exchanger while indoor air is circulated over the indoor heat exchanger andconditioned thereby.

In many air conditioning units presently on the market,

these fans are operated by asingle motor mounted within the unit. This fan motor, inmanypresent air conditioning units, may be operated at high speed in order to provide high capacity output from the unit or maybe operated at a lower speed whenever high capacity output is not needed and it is desirable to reduce the noise outi In those units, in which both fans are operated by thesame motor, the low fan speed operation reduces thefiow-of air overthe condenser of stantial damage to the compressor if allowed to continue.

Accordingly, it is an object of the present invention to provide an improved air conditioning unit having fans driven bya single fan motor which may be conditioned to operate at different speeds except when overload conditions exist on the high pressure side of the refrigeration system within the unit.

A more specific object'of the present invention is to provide an airconditioning unit having means, responsive to overload conditionsin the refrigeration system of the unit,'for automaticallyover-ridingthe manual fan motor control and conditioning the fan motor for high speed operation.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which. characterize the invention will be pointed out with particularity in the claims annexed to and forming apart of this specification. I

jln'carrying out the objects of the present invention there is provided an air conditioning unit of the selfcontained-type including a case adapted for mounting in an outer wall of a room and having compartments therein communicating respectively with room air and outdoor air. The unit includes a refrigeration system having heat exchangers mountedrespectively in each of the compartments of the unit; Indoor and outdoor fans are mounted in therespective compartments and drivenby a single indoors and outdoors through the respective compartments. The fan motor is conditioned to operate at different speeds and means are provided for manually changing the fan motor speed according to the desires of the operator. Means are provided in the unit for over-riding the low speed operation of the fan whenever temperature or pressure conditions in the high pressure side of the system are such as to indicate overload conditions. For a better understanding of the invention, reference may behad to the accompanying drawing in which:

FIG. 1 is a cross-sectional view showing an air conditioning unit of a self-contained type to which the present invention may be adapted;

FIG.- 2 is a diagrammatical view illustratingthe electrical circuitry of the air conditioner and illustrating an arrangement for over-riding low speed fan operation whenever overload conditions exist on the high pressure side of the system; and

FIG. 3 is a diagrammatical view of a portion of the refrigeration system showing a pressure responsive means window or opening in an outer wall of a room or enclosure. The unit is enclosed within a caseZ which, in

the illustratedembodiment of the invention, is divided by abarrier 3 into apair of separate compartments, hereinafter referred to as the inner or evaporator compartment 4 and the outer or condenser compartment 6. The unit is provided with a pair of heat exchangers 7 and 8 mounted respectively within the inner and outer compartments 4 and of The heat exchangers? and Sare connected in refrigerant flow relationship by suitable tubing (not shown) toa compressor 9, which is also disposed'in the outer or condenser compartment 6.

In order to'circulate air streams through the inner and outer compartments 4 and 7, there are provided a pair of fans'lil and-:12 mounted respectively within the inner and outer compartments and arranged to be'driven by a common motor 13 which, in the illustrated embodiment of the invention, is mounted in the barrier 3 of the unit. The

; fans are mounted on opposite ends of a common shaft 14 within the enclosure through the heat exchanger or evaporator 7 into the inner compartment .4. This air stream is directed rearwardiy. against the barrier 3 and diverted upwardly along thebarrier to be discharged back into the enclosure again through the upper portions of the unit, as indicated by the arrows inFIG. 1.

When an air conditioning unit of thistype is utilized for cooling an enclosure, the heat exchanger'7 is operated as an evaporator to extract heatfrom the air circulated through the evaporator compartment 4 and over the heat exchanger 7 fromwithin the room. The heat exchanger 8 is operated as a condenser and discharges heat taken up by the refrigerant flowing through the evaporator 7 to-the outdoor air circulated through the outer compartment 6. The outdoor air cools the condenser 8, thereby condensing the high pressure, high temperature refrigerant flowing into it from the compressor 9. Suitable means are provided, such as the capillary tube 10 (see FIG. 2), for providing apressure drop between the evaporator 7 and the condenser 8 to promote vaporization ing as well as cooling for the enclosure.

form some of the components of the air conditioning unit,

power is supplied to the compressor 9 through the power lines marked L and L Connected in series with the compressor 9 is the main switch 1 of the unit and a thermostat 20 which cycles the compressor on and off in accordance with the temperature of the room air.

As thus far described, this particular structure of the air conditioner is not considered essential to the invention, but is intended only to be illustrative of the type of air conditioner to which the invention may be adapted. It should be understood that the invention is also applicable to those types of air conditioning units having reversible refrigeration systems and used to provide heat- As will now be explained the present invention relates to over-riding means for over-riding the manual fan motor control means so that the fans are operated only at high speed whenever overload conditions exist in the refrigeration system.

Many of the air conditioning units of this general type now on the market provide a means for reducing the speed of the fans in order to reduce the noise output of the unit, whenever the cooling requirements within the room are such as to permit reduced capacity operation of the unit. In the illustrated embodiment of the invention, a fan speed control means 15, having a knob a accessible from the front of the unit, is provided for changing the motor speed according to the desires of the operator. Referring now to FIG. 2, the fan speed control means 15 includes a fan speed selector switch 16 which, in the illustrated embodiment of the invention, is movable between a pair of contacts 17 and 18 to connect either of a pair, of fan circuits across the power supply lines L and L The first circuit, which will be referred to as the high speed circuit, is energized when the selector switch 16 is connected across contact 17. This circuit includes the line 19 connecting with one of the motor taps. In FIG. 2, the fan motor '13 is shown connected in the high speed circuit.

The second, or low speed circuit, may be energized by moving the fan speed selector switch 16 across the contact 18. Movement of the selector switch 16 is accomplished manually by turning the control knob 15a (seen only in FIG. 1) on the front of the unit. The low speed circuit includes the line 21 which conducts current to the fan motor 13 through a reactance 22 connected in series with the motor across the power supply lines.

The reactance 22, when connected in series in the fan circuit reduces the fan speed and achieves a reduction in the noise output of the unit. Any type of reactance may be used, such as an inductive or capacitive reactance or some combination of these. In the illustrated embodiment of the invention, an inductive reactance is shown which is capable of reducing the fan speed without creating too great a power loss or heat dissipation in the reactance itself. It will also be understood that, although the reactance 22 is shown external to the fan motor 13, it may well be incorporated as a part of the fan motor, such as in the form of an inductive winding in the stator of the motor itself.

Many persons operate the conditioner on low speed most of the time thereby sacrificing capacity in order to reduce the noise of the unit. When the outdoor temperature becomes very warm, this low speed operation of the condenser fan 12 does not supply the necessary air flow to properly cool the condenser. At these times, the high pressure gas does not condense at a fast enough rate and the pressure in the high side of the system, rises substantially. The high pressure side of the system includes all of the system from the capillary 10 back to the outlet of the compressor. The high pressure in this part of the system results, at times, in overload conditions which are likely to damage the compressor motor or cause the a! motor overload protector to interrupt the power to the compressor.

Referring again to FIG. 2, itm ay be seen that there is also connected'in series in the low speed circuit to the fan motor 13, a low speed over-ride control means or override switch device 23. The over-ride switch device 23 is responsive to overload conditions in the refrigeration system and operates to shunt current around, or to bypass, the reactance '22 in the low speed circuit whenever overload conditions exist. The low speed over-ride control means includes an over-ride switch 24 operated between a pair of contacts 26 and 27 by a thermal or pressure responsive device, which senses the temperature or pressure of the discharge line 28 leading from the compressor 9 to the condenser 8. The arrangement of FIG. 2 illustrates a thermal responsive device including a bulb 29 disposed adjacent the discharge line 28 for sensing the temperature of the discharge line. The bulb 29 is connected by means of tubing 31 to a conventional fluid type responsive member or bellows 32. As is well understood in the art, the pressure within the bellows 32 is a function of the temperature of the bulb 29 and this pressure causes the bellows 32 to operate the switch 24 whenever a predetermined temperature occurs in the discharge line 28. The predetermined temperature, of course, is one calculated to prevent overloading of the compressor motor due to insufiicient condensation in the condenser 8 as a result of insufficient air flow thereover.

If the speed selector switch were positioned, as indicated in the dotted line position of FIG. 2, and switch 24 were connected across contact 26, then the fan motor would operate on low speed. However, when the temperature of the discharge line becomes too great, the bellows 32 moves the switch 24 across the contact 27 thereby conducting current through the bypass line 33 to the high speed tap of the motor. This increases the air flowing over the condenser 8 and results in greater cooling of the condenser thereby relieving the overload conditions in the high pressure side of the refrigeration system and lowers the temperature and pressure in the discharge line 28.

FIG. 3 illustrates a similar low speed over-ride control means in which a pressure responsive device or unit 34 is used to sense overload conditions in the discharge line 28. These devices are well known in the art and sometimes include a diaphragm, disposed within the hermetically sealed unit 34, that moves in response to a predetermined pressure condition being sensed by the device 34. The pressure responsive device used for this purpose may be any of the well known types presently on the market and should preferably, be provided with means for adjusting the device to operate the switch 24 at a predetermined operating pressure. In the embodiment of the invention shovm in FIG. 3, the switch 24 is shown schematically as being external to the pressure responsive device 34, however, in practice, this switch would probably be a part of the hermetically sealed unit and only the lines leading to the fan motor 13 would be external to the unit. The pressure sensed by the pressure responsive device 34 is, of course, indicative of approaching overload conditions in the high pressure line 28. When a pressure, of an amount calculated to approach overload conditions for the compressor motor, is experienced by the pressure responsive device 34, it moves the switch 24 across the contact 27 thereby removing the reactance 22 from the fan motor circuit and connecting the fan motor for high speed operation.

It will be understood that, although the described fan motor operates at only two different speeds, it could just as well have several diflerent speeds with the lower speed circuits all being by-passed or over-ridden by the override switch 24, whenever overload conditions are sensed in the discharge line 28.-

By the present invention there is provided an improved air conditioning unit having a pair of fans operated by a motor, adaptable to two or more dilferent operating speeds, and including automatic means for preventing overloading of the refrigeration system of the unit due to low speed operation of the fans when conditions are such as to require high speed operation of the fans.

While in accordance with the patent statutes there has been described what is considered to be the preferred embodiments of the invention, it will be "understood by those skilled in the art that various changes and modifications may he made therein Without departing from the invention, and it is, therefore, the aim of the appended claims to cover all such changes andmodifications as fall Within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An air conditioning apparatus for conditioning the air within an enclosure comprising a casing adapted for mounting in an outer Wall of an enclosure; said casing having portions thereof exposed to indoor and outdoor air; a refrigeration system in said casing including a com pressor, acondenser, expansion means and an evaporator connected in refrigerant iioW relationship; a gas discharge line connected between said compressor and said condenser; an evaporator fan and a condenser fan adapted to circulate separate air streams over said evaporator and said condenser respectively from Within said enclosure and from the outdoors; a single motor mounted in said casing for driving both ofsaid fans; manually operated speed control selector means accessible from the front ,Of said unit for manually connecting said fan motor into first or second fan motor circuits; said first fan motor ciradapted to. actuate said over-rideswitch means to discon nect said reactance upon the occurrence of a predetermined temperature in said discharge line indicative of overload conditions in said system so that said fans are always operated at maximum speed Whenever overload conditions exist in said refrigeration system.

2. An air conditioning apparatus for conditioning the air within an enclosure comprising a casing adapted for mounting in an outer Wall of an enclosure; said casing having portions thereof exposed to indoor and outdoor air; a refrigeration system in said casing including a compressor, a condenser, expansion means and an evaporator connected in refrigerant flow relationship; a discharge line for conducting high pressure discharge gas from said compressor to said condenser; an evaporator fan and a condenser fan adapted to circulate separate air streams over said evaporator and said condenser respectively from Within said enclosure and from the outdoors; a single motor mounted in said casing for driving both of said fans; manually operated speed control selector means accessible from the front of said unit for manually connecting said fan motor into a first fan motor circuit or a second fan motor circuit; said first fan motor circuit adapted to operate said fan motor at maximum speed; said second fan motor circuit including a reactance therein adapted to reduce the speed of said fan motor as compared to the operating speed of said fan when connected in said first fan-motor circuit; over-ride switch means. connected in said loW speed fan circuit for disconnecting said reactance from said low speed fan circuit thereby to operate said fan motor at maximum speed; a pressure responsive device in said high pressure line; said pressure responsive device adapted to actuate said over-ride switch means according to a predetermined pressure indicative of overload conditions in said refrigeration system sothat said reactance is disconnected from said low speed fan motor circuit and said fan is operated at maximum speed Whenever overload conditions exist in said refrigeration system.

References Cited in the file of this patent UNITED STATES PATENTS 2,361,090 Dickey Oct. 24, 1944 

